Author Topic: DIY Kart Sim Rig (racing rig made from old kart chassis)  (Read 1628 times)

ruanp28

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DIY Kart Sim Rig (racing rig made from old kart chassis)
« on: August 18, 2016, 10:26:03 AM »
Hi guys, so I decided to do a detailed DIY of my kart sim project, since there is literally only a handful on the internet.

After doing some research, I found that the Internet does not have many DIYs on using a kart chassis as a sim rig (for karters or those who like the feel of a kart, this sim concept will really make you smile). Now, before reading any further, please note that I am writing this DIY because I know there must be others out there who want a low-cost solution, especially for those who are either not too serious in sim racing, or those who cannot afford purchasing top-end sim equipment. I would like anyone who reads the DIY to also add their own creativity and if there are ways you think it can be improved, feel free to speak out, since this was all thought out while I was going along, nothing was planned or drawn on paper beforehand. Also note that this is my first ever DIY, and I am not a professional blogger, but a simple weekend racer/9 to 5’er enjoying sim racing in my spare time, who thought it would be nice to create a DIY since I was struggling to find an existing one – so if I can help anyone out there who was looking for such a rig, my efforts in starting this thread would not have been for nothing. Now that we have that out of the way, if you are still interested in the DIY, welcome :)

This is a “poorman’s kart rig”, which I made from scraps lying around the garage, I did not purchase a single thing yet. As such, the sim is only in “alpha phase” if you will. I used a simple Logitech Driving Force GT for the sim, without a clutch or anything fancy. As soon as I test the sim, I will start making special brackets to hold everything in place neatly and cover up everything, including giving the frame a fresh coat of paint etc etc.

1: Pedal to the metal

I decided to use the kart’s pedals instead of the plastic Logitech pedals. To do this, I had to remove the “pots” after I did some research on how they work. It is basically like a volume knob, but with a spring that returns it to position 0. I decided that I will mount these little pots to the chassis and connect each to the throttle and brake (hydraulic) on the chassis, making it much more realistic than the plastic Logitech pedals.
Step 1: Remove the bottom plate of the Logitech pedals. It is just a bunch of screws, after it is removed and the pedals are turned over, this is what you will see. The pots are linked to the pedals via small gears, which won’t be needed in my current setup. The pots are attached with two small screws as seen in the picture.



One problem that I found is that the pots are connected to one another with a very short wire – now, if you want to keep your warranty, the rest of this post will be irrelevant, since I decided to cut these wires in order to attach the pots on opposite sides of the kart chassis. Seeing as the DFGT is a cheap wheel, I wasn’t bothered by cutting three little wires 
 
The picture below shows the wires that link the pots. I basically just extended these wires, so I cut them. This was only to test the concept, so another option is to create an extension with similar connectors as seen on the pots, basically just creating extension wires with male tips on the one end, and female tips that “click” onto the pots on the other end, this will then result in no cutting – however, when I tried to loosen the little female clips from the pots, it felt like I am going to break off something so I cut the wires instead of running risk to damage the pots.
Step 2: The red, black and green wire from the brake pedal pot was cut, and will be extended to the throttle pot. Important to notice with these pedals is that the accelerator pot is the pot connected to the plug that goes into the wheel and it has 2 red wires and 2 black wires instead of one, so do not cut any wires at the accelerator pot, rather cut at the brake pot.



Now the pots were freed from one another and I removed them from the plastic casing. This is completely reversible should you want to use the plastic pedals again, you will just put the pots and pedals back into place as you removed them 

Since I just decided that I am going to write a DYI on it, I did not take detailed pictures of how everything works, so I will take some tonight and post them over the weekend. But, I will put my paint drawing skills to use, to give an idea of what I did. Again, this is till only a concept, as soon as I get everything to work flawlessly, I will make nice brackets to clean up everything. I will also be using throttle cable to link the pots to the separate pedals. At the moment, I simply used fishing line to connect the pots to the pedals, since it can be tied around the pedals and pots, and cut off as soon as I can see everything is working. You can off course use any form of linkage between the pots and pedals that you wish, I just feel that throttle cable will be the easiest since it can be sleeved in the plastic shield and zip-tied neatly to the chassis.

1.1: How the Logitech DFGT pot works
The pot basically works like a small volume knob on a radio, except when you turn the volume up and release the knob, it will turn itself back down. The green arrows (thanks to my paint skills) show how the pod moves forward or backwards when pulled. Pulling it forward (arrow facing left) increases brake/acceleration and vice versa.


 
After figuring out how the pots work, it was easy to decide where they should be mounted. As long as the pots are mounted in a way so that the push of a pedal can pull the pot’s “arm”, you are ready to go!

1.2: Brake pedal

The image below shows the pot at the brake cylinder, it works as follows – as soon as the brake pedal gets pushed forward, the line between the cylinder’s arm and the pot’s arm pulls the pot forward, mimicking the push of the plastic Logitech pedal downwards. It still looks messy, because I only tested whether it works and whether the pc picks up the movement of the brake pedal when pushed forward. As soon as I pull the kart’s brake pedal, the meter on the Logitech software on my PC ran up, indicating a perfect linear response. Let go of the pedal and the pot returns back to position 0. It is important that the kart’s pedals have springs attached to the chassis (as they come from factory), to ensure that the pot’s little spring doesn’t have to pull the metal pedal backward. At the moment, there is very little stress put on the pots, I reckon even less stress than were put out by the original plastic pedals with gears.


 
Although everything still looks like crap, it was only to test out whether the idea works. And it does pretty well indeed  To give an idea of the bracket at the brake pedal, here is a picture of it from the other side of the cylinder (before I screwed it in place – just used glue gun to line it up):


 
After hooking up the pod and lining it up in order for the brake pedal to pull the pot’s arm, I went to the other side of the chassis, where the throttle will be located.    

1.3: Throttle Pedal

The idea is to use the existing throttle cable on the kart (that was linked to the engine’s carby which I removed), and link the cable to the pot. The best position I could find at the moment with the brackets that I had lying around, was right next to the seat (fastening the bracket to the existing seat bolt). The principle remains the same : position the pot so that pushing the throttle pedal forward, pulls the pot’s arm forward as well. The image below shows the pot being fastened to a bracket that I bent and drilled small holes into – at the moment I also just attached fishing line, since it was 11 pm and I just wanted to test it and get it done with. I am going to make a proper bracket and linkage so that the throttle cable can be linked to the pot’s arm properly.



After both pots were positioned and lined up with the kart’s pedals, the wires that were cut earlier (green,black and red) need to be connected again so that the pots can work. To do this, I took an old usb cable and cut off both ends, and used three of the four wires inside and soldered both ends to the wires on the pots. You can use any electrical wire, just make sure not to have any of the ends open or touching metal, to prevent a short.

That is it for the pedals, I tested them and they work perfectly on my PC. The next step with the pedals are to link the pots with the pedals via proper cabling and sleeves, making brackets that look better and hold the pots firmly in place and lastly covering the pots so that only the cables are visible after I am done. However, that will only be done as soon as the frame is re-sprayed and everything is clean.

2: Steering

The steering wheel is the tricky bit, which I haven’t really started with yet. There are two options, each with their own pros and cons, depending on what type of sims you intend to play:

a)   Use the Logitech wheel as is, and simply mount it after removing the kart’s steering wheel and column.
b)   Use the kart’s wheel and steering column, and create an adapter that will attach to the Logitech housing (requires removing the Logitech wheel from the housing).

Option A is for those who prefer not to disassemble their wheel and would like to make use of the buttons on the wheel (for example the shift paddles). At this moment, I opted for option A since I have not put enough time into thinking how I am goig to extend the steering rod, create an adapter and attach the Logitech housing under the kart’s chassis (requires me to make a hole in the kart’s floortray and lifting the entire chassis). There might be another option, to put the housing closer to the top of the kart’s existing wheel, and create a short steering rod to connect to the housing – still, it is a project for another day. I only got the chassis on Tuesday, so on Tuesday night and last night, this was the best that I could come up so far.

I removed the bib (nosecone) of the kart and used the bracket that holds the bib up to mount the steering wheel. I plan on cutting out a piece of wood and screw it to the brackets of the bib, in order to create a little platform for the wheel to clamp onto. As soon as I am done with this, I will post more images. At the moment, I just used two small pieces of wood and it works. You can create any bracket to hold the wheel, and with more time I probably will as well. The part of the chassis that holds the steering column in place has 2 holes in it, making it possible to create a small “shelf” to mount the wheel onto.

I am going to test the sim tonight, and will give feedback as soon as possible. This project has only started, and I intend to keep updating the thread if there is any interest. I hope I can help someone who also got tired of searching forums for kart builds like I did. Below is a picture of the rig as it stands now (please keep in mind I only worked on it for 2 evenings so far after I got home from work, so it is still far from done, but hopefully it will be helpful to fellow karters/sim racers).


 
NOTE: I am not sure whether the pictures work or not, this is my first DIY post ever :) If they dont work feel free to tell me where I should upload them instead.
« Last Edit: August 18, 2016, 01:13:22 PM by ruanp28 »

Cory_Hayes

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #1 on: August 18, 2016, 11:00:56 AM »
Pictures don't appear to be working

ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #2 on: August 18, 2016, 12:07:29 PM »
Fixed them :)
« Last Edit: August 18, 2016, 01:17:32 PM by ruanp28 »

ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #3 on: August 18, 2016, 12:29:58 PM »
Since its only been 2 evenings, I must say I am quite optimistic about it. Will work in it some more this weekend, the only fork in the road at the moment is deciding between using the kart's wheel (making it the perfect replica, but also without gear shifting capability) and connecting the rod (and loose the paddle shift buttons and other controls on the wheel). Maybe I will add paddles and connect it to buttons later on, at the moment I will focus on fitting the Logitech wheel.

I am still deciding what the monitor/s will be, since I have three options at my disposal -

I have a 55" TV, which I can use since I have a head tracking device to look to the apex. Also something I made myself using a Sony PS3 eye camera and 3 IR LEDs :)

I also have a cinema room with a projector, but personally I think its too big

Lastly, my dual 22" monitor setup, also with head tracking (what I use at the moment, works amazingly, haven't felt the need for triple screen due to the tracker).

Your input is greatly appreciated, and I hope this might help someone looking to do something similar in the future!
« Last Edit: August 18, 2016, 01:16:31 PM by ruanp28 »

EVO

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #4 on: August 18, 2016, 11:27:15 PM »
Your setup is pretty simiar to mine. Sell the tv and get the oculus rift.  Thats what i plan to do. U went through alot of effort to get pretty direct connections to your  digital inputs. Check out my rig. http://forum.kartracing-pro.com/index.php?topic=1385.msg9836#msg9836
I went the super cheap reversable route. But the feel is pretty good as long as the weighted digital pedal stand stays in place and the tension in the wire to the kart pedals  stays the same.

The next level is having a photo sensor in the airbox to sense choking. Two on the radiator one on the top and one on the bottom to sense radiator cover adjustments and one in the middle for radiator hand covering. Buttons on the brake master cylinder for brale bais  adjustments. A normally closed switch in the back of the seat to sense tucking when you lean forward.  Last but not least a real kart shifter, clutch lever, and a real kart wheel attached to a shaft and the motor relocated under the kart floor pan. Ive seen some of these implemented.  Im thinking a old keyboard (practically free) can be hacked up to run wires to buttons and then apply those buttons in game. Just some food for thought. You sim rig is coming along so  i figured id offer some next level suggestions. 
« Last Edit: August 18, 2016, 11:51:20 PM by EVO »
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ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #5 on: August 19, 2016, 07:42:41 AM »
Thanks for the input, I really appreciate it.  :)

I agree with adding the kart's original wheel, I have started with some ideas to mount the unit underneath the floortray and extend the rod from there. The only thing stopping me is the fact that there might be some flex due to the long shaft, but I guess an extra carrier with a bearing or something can sort that out. As for the Oculus Rift, I have one and I can only play some games on it designed for it. I have tried racing games on the Rift, let's just say my stomach couldn't handle it after 5 laps. So I will probably go with monitors and head tracking.

I tested the setup last night on KRP and I must say, it feels a lot more like a karting sim now than it did in my playseat. The fact that the master cylinder for the brake is still being used is also more realistic than having to push down on a flimsy plastic brake pedal. For now I am going to mount the wheel as it is to the kart, just to show others that might have the same idea how I am doing it. If you dont mind, would you like to share how you mounted your wheel to the kart? After the wheel is added and I have one option of using the rig, I will start working on using the kart's original wheel and adding some sort of button for paddles.

I like the idea that you have of using sensors for choke and tucking in etc., since I drive a paddle shift kart (Rotax DD2) I will probably not go into that much detail. I am going to subscribe to your thread, hope you keep updating it. I will be posting some more pictures tomorrow after fitting the wheel to the kart, at the moment the easiest solution would be to use a small piece of wood to create some sort of "table top". - The reason I am doing it like this is because I want to keep to what my original intentions were, and that is to keep the cost of the rig as affordable as possible for other sim racers that do not have a ton of money lying around. Those that actually race on weekends usually spend all their money on racing, so sims are usually not at the top of the budget list :)

Anyways, I will send pictures of the wheel attached over the weekend as I am moving along. For now, here is a to-do list still to come:

> Clean the damn thing, since I only pulled off the engine and wheels after purchasing it
> Create better, sturdier brackets for the pots
> Link the pots' arms with the pedals via a thin rod ie. those used on r/c aeroplanes (for the brake) and throttle cable (for the throttle)
> Lining the seat with HD foam (I thought of replacing the seat with my DD2's Tillet and buying a new one for my DD2, but... meh)
> Cleaning the chassis and adding the plastics and wheels again (not entirely sure yet, might keep them removed to keep rig "slim")
> Lifting the rig off the ground in order to compensate for future installation of FFB steering base under floortray
> Creating some sort of holders that keep the pots hidden and unexposed, with small openings for the rod/cable coming out only
> Maybe add some trolley wheels at the bottom so that rig can be lifted and stored away (might be an issue if I want to lift the rig off the ground)

So there is still a lot to be done, but I feel it is going to be interesting. Doing all of this while keeping costs low is going to be a challenge, but I am up for it. I could go out and buy a ton of steel and button boxes and weld everything etc etc. but then it will just be another expensive rig, and my post would be of no use to anyone that is on a budget. So I will keep on doing it as neatly as possible, with as many "scraps" lying around as possible. As of this moment, the only expense was buying an old 100cc kart (which you dont have to do, a bare chasssis with a seat and pedals is all you need)

Cheers for now  ;)
« Last Edit: August 19, 2016, 07:47:54 AM by ruanp28 »

ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #6 on: August 29, 2016, 03:13:58 PM »
I know nobody probably follows this thread, but just an update - I bought a third screen for triple monitor setup after contemplating other options, which fell off from the table due to me being clumsy and tripping over the wire on the ground. New monitor = cracked. So, I bought another cheap monitor until I can forgive myself :)

I decided to make a steering boss for the wheel and added my kart's wheel instead of an extended shaft, and it feels perfect. I went this way since I don't want to lift the whole chassis, and because I don't see the need to use an additional steering shaft when the wheel can detach.

I also built a small stand that the three monitors can stand onto, and the chassis goes under the stand with the front wheels under the screens. So far, nothing has broken (except my new screen  :'( ) or come loose, and the pedals are solid and connections to the pots are great. I want to replace the fishing line with something stronger, but I tried cables and it doesn't work - the cable is just too heavy for the little pots.

To save space I decided not to add the kart's plastics or rear wheels.

I will post pictures of everything mentioned above soon...

Still to come:

> Alternative connections to the current fishing lines
> DIY shfting paddles
> Pot covers and brackets
> Stand needs to be painted black and covered

EVO

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #7 on: August 30, 2016, 03:52:07 AM »
Does your wheel have a crazy male fitting that goes into the motor shaft?  Is your boss fit in it or matches the screw pattern?
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EVO

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #8 on: August 30, 2016, 03:57:05 AM »
https://www.gtplanet.net/forum/threads/driving-force-pro-mod-a-reason-to-buy.42954/
This guy did something similar but matching the screw pattern alone seems insufficient. I connected Logitech for their male fitting dimensions but they wouldn't release It   Can we see your adapter?
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Cory_Hayes

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #9 on: August 30, 2016, 06:47:14 AM »
Just in regards to the kart wheel being on a sim wheel, just thought I would show this here.
I had a steering wheel laying around from one of my old karts a few years ago ( Arrow AX9 ) so I decided to slightly drill the holes out and put it onto my G27, I did have the buttons setup but then I went back to a G27 rim for iRacing and had to put them back on there, but yeah, been running the Kart wheel on my G27 since late 2012.
* Note, sorry about the quality, didn't exactly focus it too well because was in a rush *

ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #10 on: August 30, 2016, 08:18:38 AM »
Hi guys,

I actually did something really simple - pics with the rest of the tutorial will be posted very soon, I made sure to take pics as I went along. Anyways, since my original goal was to buy absolutely nothing, I made a steering boss from an old PVC round box lying in the garage. When you remove the Logitech wheel (it attaches with only four screws), it has 4 holes where self taper screws turn into. So I took the plastic round box, drilled 4 holes into it to attach it to the Logitech base. After that, I drilled 3 holes through the PVS round box (aka my poorman's steering boss), and the wheel is attached to it via three small bolts with locknuts.

There is absolutely zero flex or play, it works perfectly since the roundbox is quite strong, and it also spaces the kart's wheel away from the Logitech base. So my old wheel can attach to the base again, completely reversable and the only drilling that took place was through the PVC round box.

ruanp28

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #11 on: August 30, 2016, 12:16:31 PM »
Okay, time for some progress updates... in this part I will explain (as best as I can) how I mounted the kart's steering wheel on the Logitech base and how I mounted the base to the kart so that it is secure...

1. Mounting the base to the kart:

In order to mount the base to the kart, I simply tried to create a small "table top" onto which the base can attach. There are plenty of different ways to do this, but I used what I had in front of me. I decided to take the brackets that hold the kart's bib in place (the nose cone) and faced them backward to the seat (as seen in the picture below):



These brackets are solid and when tightened they wont move down even when I tried pushing them down, so there was no need to build support struts of any kind :)

After the brackets were bent backward, I took a small piece of wood (plankie), and positioned it on top of the brackets to see if the wheel will be able to be fastened to it. And what do you know - it worked like a charm. As seen in the picture below, the base fits perfectly. After I fit it, I made some L-brackets to attach the wood to the brackets, and I also cut the wood in the shape of the base so that it has no sharp parts sticking out. I also cut off the part of the steel brackets that were sticking out underneath the base.





There are plenty of other ways to do this, but this method works so I am sticking with it. I intend on covering the wood with black vinyl sticker so that it looks nice and tidy. Now that the base was attached to the kart, the next step was to get a nice suede racing steering wheel on there....

2. Mounting the kart's steering wheel to the Logitech base:

In order to mount the kart's wheel, I had to remove the original wheel from the Logitech base. This was fairly easy, since the wheel just attaches to the base via 4 screws and a small connector plug for the buttons. The center button clips loose (I used a small surgical blade to pop it loose) and then you can see the screws that need to be loosened. As soon as you loosen the screws, there is a small connector plug for the buttons. Simply unplug it and your wheel is now loose.

After this, you will have only the base with 4 holes as seen in the pictures below:







Now that the wheel was off, I needed to figure out a way to get the kart's steering wheel onto the base of the Logitech. My original goal was (and still is) to only use stuff lying around the house, so I started looking in the garage...I found a PVC round box and decided that this will be my steering boss.

What I did was really simple - I drilled holes into the back of the PVC round box. 4 Holes for it to screw onto the Logitech base and 3 holes for the kart's steering wheel to be bolted with small bolts and lock nuts. The picture below shows the round box and where I made the holes.



It is really simplistic and there are a ton of better ways probably to do it, but my idea was not to spend money. You can always get a thick piece of plastic disc and drill holes into it (for example round plastic drink coasters) or machine something out of aluminium. My point is - there are plenty of ways to improve it, and your feedback is as always appreciated. I went with the round box since we had plenty lying around :)

I screwed the round box onto the Logitech base after I switched it on so that the Logitech is in position zero. After the round box was attached to the Logitech base, I lined up the kart's steering wheel and drilled the holes and fastened it with 3 long bolts and small 10 size lock nuts. There is absolutely zero flex or weakness and it works perfectly thanks to the strong PVC material. It also spaces the kart's wheel from the base so that the wheel is close to me (since you lie back in a kart).

The image below shows the wheel fitted to the base (the round box is being removed this weekend to get a black coat of spray paint ) :)



Now that this part is out of the way...I will start making a tutorial of the rest of the build. Until then, at the bottom of this reply is a picture of the rig as it is at the moment...

Next pictures still to come will be where I modded the pots a little to be attached to the pedals, and my simple home-made stand that I made so that it is low enough to be at eye level when the kart is on the ground.

List of unfinished things:

> Better brackets for the pots, and covering them up so that only the links to the pedals are exposed
> Wrapping the stand for the screens in black
> The stand will get finishing touches so that the legs cannot be seen
> Seat needs to be lined with HD foam
> Clean the damn thing (again)   

Here is a pic that was taken in the back of my garage after it was built to test it. As you can see, I removed all the plastics (side pods and front bumper) to keep it small and compact. It looks much better with the plastics on, but unfortunately my fianceé doesn't agree   




 


matty0l215

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #12 on: August 30, 2016, 03:34:51 PM »
Although I don't race in KRP, I've always wanted a proper rig to drive in and im loving this!! ;D

Keep it up :)

phil#14

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #13 on: November 05, 2016, 09:22:36 PM »
Hi ruanp28,
Thanks for this informative and inspirational info. This is exactly what I want to do and it's great that the thread isn't 10 years old, like many of the links the search engines suggest ! I don't suppose anybody knows if the 15 year old original XBox Gamester Lotus wheel & pedals would work with Kart Racing Pro if I purchased a universal XBox/USB adapter ? Any updates on progress ? I have no gaming gear at all (apart from my 15 year old XBox that I never used), so am starting from scratch and thinking Oculus Rift may be an easier way to go than 3 monitors, a frame/rig and surround speakers ?

bart

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Re: DIY Kart Sim Rig (racing rig made from old kart chassis)
« Reply #14 on: May 12, 2017, 02:36:49 PM »
this looks class i am going to look into this for my son to make it on a bambino !! great work